This invention relates to circuitry for protecting integrated circuit components such as fuses from damage due to electrostatic discharge.
Integrated circuits are often exposed to potentially damaging electrostatic charges. For example, a wafer of integrated circuits may be exposed to electric charges during fabrication. Such charges may arise from the use of plasma etching techniques or other processes that produce charged particles. As another example, a packaged integrated circuit may be exposed to electrostatic charges when a worker inadvertently touches exposed pins on the circuit's package or when the package becomes charged electrostatically due to movement of the package in a tray.
These electrostatic charges can damage sensitive circuitry. For example, transistors and other electrical devices on an integrated circuit can be damaged when exposed to excessive currents.
Some integrated circuits have programmable fuses or antifuses. Fuses and antifuses may be used, for example, to selective switch redundant circuitry into use in place of defective circuitry. Fuses and antifuses may also be used to store information on an integrated circuit (e.g., a secret key, a serial number, etc.). If exposed to unwanted currents, the fuses or antifuses on an integrated circuit may be inadvertently programmed. Inadvertent programming of the fuses or antifuses may render the circuit inoperable.
It would therefore be desirable to provide circuitry for protecting integrated circuits against the harmful effects of electrostatic discharge.